System and methods for determining nerve direction to a surgical instrument
System (20) and related methods for performing surgical procedures and assessments, including the use of neurophysiology-based monitoring to determine nerve proximity and nerve direction to surgical instruments (30) employed in accessing a surgical target site.
Latest NuVasive, Inc. Patents:
This application is a continuation under 35 U.S.C. 111(a) of PCT Patent Application Serial No. PCT/US03/02056, filed Jan. 15, 2003 and published on Aug. 5, 2004 as WO/04/064634.
BACKGROUNDSystems and methods exist for monitoring nerves and nerve muscles. One such system determines when a needle is approaching a nerve. The system applies a current to the needle to evoke a muscular response. The muscular response is visually monitored, typically as a shake or “twitch.” When such a muscular response is observed by the user, the needle is considered to be near the nerve coupled to the responsive muscle. These systems require the user to observe the muscular response (to determine that the needle has approached the nerve). This may be difficult depending on the competing tasks of the user. In addition, when general anesthesia is used during a procedure, muscular response may be suppressed, limiting the ability of a user to detect the response.
While generally effective (although crude) in determining nerve proximity, such existing systems are incapable of determining the direction of the nerve to the needle or instrument passing through tissue or passing by the nerves. While the surgeon may appreciate that a nerve is in the general proximity of the instrument, the inability to determine the direction of the nerve relative to the instrument can lead to guess work by the surgeon in advancing the instrument, which raises the specter of inadvertent contact with, and possible damage to, the nerve.
SUMMARYThe present application may be directed to at least reduce the effects of the above-described problems with the prior art. The present application includes a system and related methods for determining the direction of a surgical instrument to a nerve during surgical procedures. According to one aspect of the system, this involves the use of neurophysiology-based monitoring to determine nerve direction to surgical instruments employed in accessing a surgical target site. The system may do so in an automated, easy to use, and easy to interpret fashion so as to provide a surgeon-driven system.
The system may combine neurophysiology monitoring with any of a variety of instruments used in or in accessing a surgical target site (referred to herein as “surgical access instruments”). By way of example only, such surgical access instruments may include, but are not necessarily limited to, any number of devices or components for creating an operative corridor to a surgical target site, such as K-wires, sequentially dilating cannula systems, distractor systems, and/or retractor systems. Although described herein largely in terms of use in spinal surgery, it is to be readily appreciated that the teachings of the methods and systems may be suitable for use in any number of additional surgical procedures where tissue having significant neural structures must be passed through (or near) in order to establish an operative corridor to a surgical target site.
A general method according to the present application may include: (a) providing multiple (e.g., four orthogonally-disposed) electrodes around the periphery of the surgical access instrument; (b) stimulating the electrodes to identify the current threshold (IThresh) necessary to innervate the muscle myotome coupled to the nerve near the surgical access instrument; (c) determining the direction of the nerve relative to the surgical access instrument via successive approximation; and (d) communicating this successive approximation direction information to the surgeon in an easy-to-interpret fashion.
The act of providing multiple (e.g., four orthogonally-disposed) electrodes around the periphery of the surgical access instrument may be accomplished in any number of suitable fashions depending upon the surgical access instrument in question. For example, the electrodes may be disposed orthogonally on any or all components of a sequential dilation system (including an initial dilator, dilating cannulae, and working cannula), as well as speculum-type and/or retractor-based access systems. The act of stimulating may be accomplished by applying any of a variety of suitable stimulation signals to the electrode(s) on the surgical accessory, including voltage and/or current pulses of varying magnitude and/or frequency. The stimulating act may be performed during and/or after the process of creating an operative corridor to the surgical target site.
The act of determining the direction of the surgical access instrument relative to the nerve via successive approximation is preferably performed by monitoring or measuring the EMG responses of muscle groups associated with a particular nerve and innervated by the nerve(s) stimulated during the process of gaining surgical access to a desired surgical target site.
The act of communicating this successive approximation information to the surgeon in an easy-to-interpret fashion may be accomplished in any number of suitable fashions, including but not limited to the use of visual indicia (such as alpha-numeric characters, light-emitting elements, and/or graphics) and audio communications (such as a speaker element). By way of example only, this may include providing an arc or other graphical representation that indicates the general direction to the nerve. The direction indicator may quickly start off relatively wide, become successively more narrow (based on improved accuracy over time), and may conclude with a single arrow designating the relative direction to the nerve.
Communicating this successive approximation information may be an important feature. By providing such direction information, a user will be kept informed as to whether a nerve is too close to a given surgical accessory element during and/or after the operative corridor is established to the surgical target site. This is particularly advantageous during the process of accessing the surgical target site in that it allows the user to actively avoid nerves and redirect the surgical access components to successfully create the operative corridor without impinging or otherwise compromising the nerves.
Based on this nerve direction feature, an instrument is capable of passing through virtually any tissue with minimal (if any) risk of impinging or otherwise damaging associated neural structures within the tissue, thereby making the system suitable for a wide variety of surgical applications.
A direction-finding algorithm that finds a stimulation threshold current one electrode at a time for a plurality of electrodes (e.g., four electrodes) may require 40 to 80 stimulations in order to conclude with a direction vector. At a stimulation rate of 10 Hz, this method may take four to eight seconds before any direction information is available to a surgeon. A surgeon may grow impatient with the system. An “arc” method described herein may improve the direction-finding algorithm and provide nerve direction information to the surgeon sooner. The system may display direction to the nerve during a sequence of stimulations as an “arc” (or wedge), which represents a zone containing the nerve. Computation of the direction arc (wedge) may be based on stimulation current threshold ranges, instead of precise, finally-calculated stimulation current threshold levels. Display of the direction arc (wedge) is possible at any time that the stimulation current thresholds are known to fall within a range of values.
One aspect relates to a system comprising: a surgical accessory having at least one stimulation electrode; and a control unit capable of electrically stimulating at least one stimulation electrode on said surgical accessory, sensing a response of a nerve depolarized by said stimulation, determining a direction from the surgical accessory to the nerve based upon the sensed response, and communicating said direction to a user. The system may further comprise an electrode configured to sense a neuromuscular response of a muscle coupled to said depolarized nerve. The electrode may be operable to send the response to the control unit.
The surgical accessory may comprise a system for establishing an operative corridor to a surgical target site. The system for establishing an operative corridor may comprise a series of sequential dilation cannulae, where at least one cannula has said at least one stimulation electrode near a distal end. The system for establishing an operative corridor may further comprise a K-wire. The K-wire may have a first stimulation electrode at a distal tip. The K-wire may have a second stimulation electrode away from the distal tip. The K-wire may be slidably received in the surgical accessory, where the surgical accessory has a plurality of electrodes. The system for establishing an operative corridor may be configured to access a spinal target site. The system for establishing an operative corridor may be configured to establish an operative corridor via a lateral, trans-psoas approach.
The system may further comprise a handle coupled to the surgical accessory. The handle may have at least one button for initiating the electrical stimulation from the control unit to at least one stimulation electrode on the surgical accessory.
The control unit may comprise a display operable to display an electromyographic (EMG) response of the muscle. The control unit may comprise a touch-screen display operable to receive commands from a user.
The surgical accessory may comprise a plurality of stimulation electrodes. The stimulation electrodes may be positioned near a distal end of the surgical accessory. The stimulation electrodes may be positioned in a two-dimensional plane. The stimulation electrodes may be positioned orthogonally to form a cross. The control unit may derive x and y Cartesian coordinates of a nerve direction with respect to the surgical accessory by using x=iw2−ie2 and y=is2−in2 where ie, iw, in, and is represent stimulation current thresholds for east, west, north, and south electrodes. The stimulation electrodes may comprise a first set of electrodes in a first two-dimensional plane and a second set of at least one electrode in another plane that is parallel to the first plane. The stimulation electrodes may form a tetrahedron. The control unit may be configured to determine a three-dimensional vector from a reference point on the surgical accessory to a nerve.
The control unit may determine a three-dimensional vector from a reference point on the surgical accessory to a nerve by using:
The control unit may be configured to determine a three-dimensional vector from a reference point on the surgical accessory to a nerve by using:
where ix is a stimulation current threshold of a corresponding stimulation electrode (west, east, south or north), ik is the stimulation current threshold of a k-wire electrode, ic is calculated from:
The control unit may be further configured to display the three-dimensional vector to a user.
The stimulation electrodes may comprise two pairs of electrodes. The stimulation electrodes may comprise a first electrode at a first longitudinal level of the surgical accessory and a second electrode at a second longitudinal level of the surgical accessory.
The control unit may be configured to electrically stimulate a first stimulation electrode with a first current signal, determine whether a first stimulation current threshold has been bracketed, stimulate a second stimulation electrode with a second current signal, and determine whether a second stimulation current threshold has been bracketed. The first and second current signals may be equal. The control unit may be further configured to determine a first range for the first stimulation current threshold, and determine a second range for the second stimulation current threshold. Each range may have a maximum stimulation current threshold value and a minimum stimulation current threshold value. The control unit may be configured to process the first and second ranges by using
where ie, iw, in, and is represent stimulation current thresholds for east, west, north, and south electrodes. The control unit may be configured to process the first and second ranges by using
where d is a distance from a nerve to east, west, north, and south electrodes.
The control unit may be configured to process the first and second ranges and display an arc indicating a general direction of a nerve from the surgical accessory. The control unit may be further configured to electrically stimulate the first stimulation electrode with a third current signal, determine whether the first stimulation current threshold has been bracketed, stimulate the second stimulation electrode with a fourth current signal, and determine whether the second stimulation current threshold has been bracketed.
The control unit may be configured to electrically stimulate each electrode until a stimulation current threshold has been bracketed. The control unit may be configured to display an arc indicating a general direction of a nerve from the surgical accessory and narrow the arc as stimulation current thresholds are bracketed. The control unit may be further configured to electrically stimulate the first and second stimulation electrodes to bisect each bracket until a first stimulation current threshold has been found for the first stimulation electrode and a second stimulation current threshold has been found for the second stimulation electrode within a predetermined range of accuracy. The control unit may be configured to display an arc indicating a general direction of a nerve from the surgical accessory and narrow the arc as stimulation current threshold brackets are bisected.
The control unit may be configured to emit a sound when the control unit determines a distance between the surgical accessory and the nerve has reached a predetermined level. The control unit may be configured to emit a sound that indicates a distance between the surgical accessory and the nerve. The surgical accessory may be dimensioned to be inserted percutaneously through a hole to a surgical site.
Another aspect relates to a surgical instrument comprising an elongated body and a plurality of electrodes on the elongated body. Each electrode is configured to produce electrical current pulses at a plurality of current levels. At least one current level being sufficient to depolarize a nerve when the elongated body is near the nerve. The elongated body may comprise a K-wire. The elongated body may comprise a cannula. The electrodes may comprise four orthogonal electrodes in a two-dimensional plane. The electrodes may comprise a first set of electrodes in a first two-dimensional plane and a second set of at least one electrode in another plane that is parallel to the first plane. The electrodes may be configured to produce electrical current pulses round-robin at a first current level, then produce electrical current pulses round-robin at a second current level. The elongated body may comprise a sequential dilation system.
Another aspect relates to a processing unit operable to determine ranges of nerve-stimulation threshold current levels for a plurality of electrodes on a surgical instrument inserted into a body.
Another aspect relates to a method comprising providing a system operable to determine a direction of a nerve from a surgical instrument inserted in a body; and installing software in the system. The method may further comprise configuring a minimum threshold peak-to-peak voltage level of a neuromuscular response.
Another aspect relates to a method of finding a direction of a nerve from a surgical instrument. The method comprises: electrically stimulating a first stimulation electrode on a surgical instrument inserted in a body with a first current signal; determining whether a first stimulation current threshold has been bracketed by the first stimulation current signal; electrically stimulating a second stimulation electrode on the surgical instrument with a second current signal; and determining whether a second stimulation current threshold has been bracketed by the second stimulation current signal.
The first and second current signals may be equal. The method may further comprise determining a first range for the first stimulation current threshold, and determining a second range for the second stimulation current threshold, each range having a maximum stimulation current threshold value and a minimum stimulation current threshold value. The method may further comprise processing the first and second ranges and displaying an arc indicating a general direction of a nerve from the surgical accessory.
The method may further comprise electrically stimulating the first stimulation electrode with a third current signal; determining whether the first stimulation current threshold has been bracketed; stimulating the second stimulation electrode with a fourth current signal; and determining whether the second stimulation current threshold has been bracketed. The method may further comprise electrically stimulating each electrode until a stimulation current threshold has been bracketed. The method may further comprise displaying an arc indicating a general direction of a nerve from the surgical accessory and narrowing the arc as stimulation current thresholds are bracketed.
The method may further comprise electrically stimulating the first and second stimulation electrodes to bisect each bracket until a first stimulation current threshold has been found for the first stimulation electrode and a second stimulation current threshold has been found for the second stimulation electrode within a predetermined range of accuracy. The method may further comprise displaying an arc indicating a general direction of a nerve from the surgical accessory and narrow the arc as stimulation current threshold brackets are bisected.
Illustrative embodiments of the application are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. The systems disclosed herein boast a variety of inventive features and components that warrant patent protection, both individually and in combination.
The act of providing multiple (e.g., four orthogonally-disposed) electrodes around the periphery of the surgical access instrument may be accomplished in any number of suitable fashions depending upon the surgical access instrument in question. For example, the electrodes may be disposed orthogonally on any or all components of a sequential dilation system (including an initial dilator, dilating cannulae, and working cannula), as well as speculum-type and/or retractor-based access systems, as disclosed in the co-pending, co-assigned May, 2002 U.S. Provisional application incorporated above. The act of stimulating may be accomplished by applying any of a variety of suitable stimulation signals to the electrode(s) on the surgical accessory, including voltage and/or current pulses of varying magnitude and/or frequency. The stimulating act may be performed during and/or after the process of creating an operative corridor to the surgical target site.
The act of determining the direction of the surgical access instrument relative to the nerve via successive approximation is preferably performed by monitoring or measuring the EMG responses of muscle groups associated with a particular nerve and innervated by the nerve(s) stimulated during the process of gaining surgical access to a desired surgical target site.
The act of communicating this successive approximation information to the surgeon in an easy-to-interpret fashion may be accomplished in any number of suitable fashions, including but not limited to the use of visual indicia (such as alpha-numeric characters, light-emitting elements, and/or graphics) and audio communications (such as a speaker element). By way of example only, this may include providing an arc or other graphical representation that indicates the general direction to the nerve. The direction indicator may quickly start off relatively wide, become successively more narrow (based on improved accuracy over time), and may conclude with a single arrow designating the relative direction to the nerve.
The direction indicator may be an important feature. By providing such direction information, a user will be kept informed as to whether a nerve is too close to a given surgical accessory element during and/or after the operative corridor is established to the surgical target site. This is particularly advantageous during the process of accessing the surgical target site in that it allows the user to actively avoid nerves and redirect the surgical access components to successfully create the operative corridor without impinging or otherwise compromising the nerves.
Based on this nerve direction feature, then, an instrument is capable of passing through virtually any tissue with minimal (if any) risk of impinging or otherwise damaging associated neural structures within the tissue, thereby making the system suitable for a wide variety of surgical applications.
The control unit 22 includes a touch screen display 40 and a base 42, which collectively contain the essential processing capabilities (software and/or hardware) for controlling the surgical system 20. The control unit 22 may include an audio unit 18 that emits sounds according to a location of a surgical element with respect to a nerve, as described herein.
The patient module 24 is connected to the control unit 22 via a data cable 44, which establishes the electrical connections and communications (digital and/or analog) between the control unit 22 and patient module 24. The main functions of the control unit 22 include receiving user commands via the touch screen display 40, activating stimulation electrodes on the surgical access instruments 30, processing signal data according to defined algorithms (described below), displaying received parameters and processed data, and monitoring system status and report fault conditions. The touch screen display 40 is preferably equipped with a graphical user interface (GUI) capable of communicating information to the user and receiving instructions from the user. The display 40 and/or base 42 may contain patient module interface circuitry (hardware and/or software) that commands the stimulation sources, receives digitized signals and other information from the patient module 24, processes the EMG responses to extract characteristic information for each muscle group, and displays the processed data to the operator via the display 40.
In one embodiment, the surgical system 20 is capable of determining nerve direction relative to each K-wire 46, dilation cannula 48 and/or the working cannula 50 during and/or following the creation of an operative corridor to a surgical target site. Surgical system 20 accomplishes this by having the control unit 22 and patient module 24 cooperate to send electrical stimulation signals to each of the orthogonally-disposed stimulation electrodes 1402A-1402D (
The sequential dilation surgical access system 34 is designed to bluntly dissect the tissue between the patient's skin and the surgical target site. Each K-wire 46, dilating cannula 48 and/or working cannula 50 may be equipped with multiple (e.g., four orthogonally-disposed) stimulation electrodes to detect the location of nerves in between the skin of the patient and the surgical target site. To facilitate this, a surgical hand-piece 52 is provided for electrically coupling the surgical accessories 46-50 to the patient module 24 (via cable 32). In a preferred embodiment, the surgical hand piece 52 includes one or more buttons for selectively initiating the stimulation signal (preferably, a current signal) from the control unit 22 to a particular surgical access instrument 46-50. Stimulating the electrode(s) on these surgical access instruments 46-50 during passage through tissue in forming the operative corridor will cause nerves that come into close or relative proximity to the surgical access instruments 46-50 to depolarize, producing a response in the innervated myotome.
By monitoring the myotomes associated with the nerves (via the EMG harness 26 and recording electrode 27) and assessing the resulting EMG responses (via the control unit 22), the sequential dilation access system 34 is capable of detecting the direction to such nerves. Direction determination provides the ability to actively negotiate around or past such nerves to safely and reproducibly form the operative corridor to a particular surgical target site. In one embodiment, by way of example only, the sequential dilation access system 34 is particularly suited for establishing an operative corridor to an intervertebral target site in a postero-lateral, trans-psoas fashion so as to avoid the bony posterior elements of the spinal column.
A discussion of the algorithms and principles behind the neurophysiology for accomplishing these functions will now be undertaken, followed by a detailed description of the various implementations of these principles.
A basic premise behind the neurophysiology employed by the system 20 is that each nerve has a characteristic threshold current level (IThresh) at which it will depolarize. Below this threshold, current stimulation will not evoke a significant EMG response (Vpp). Once the stimulation threshold (IThresh) is reached, the evoked response is reproducible and increases with increasing stimulation until saturation is reached. This relationship between stimulation current and EMG response may be represented graphically via a so-called “recruitment curve,” such as shown in
In order to obtain this useful information, the system 20 should first identify the peak-to-peak voltage (Vpp) of each EMG response that corresponds to a given stimulation current (IStim). The existence of stimulation and/or noise artifacts, however, can conspire to create an erroneous Vpp measurement of the electrically evoked EMG response. To overcome this challenge, the surgical system 20 may employ any number of suitable artifact rejection techniques. Having measured each Vpp EMG response (as facilitated by the stimulation and/or noise artifact rejection techniques), this Vpp information is then analyzed relative to the stimulation current in order to determine a relationship between the nerve and the given electrode on the surgical access instrument 46-50 transmitting the stimulation current. More specifically, the system 20 determines these relationships (between nerve and surgical accessory) by identifying the minimum stimulation current (IThresh) capable of producing a predetermined Vpp EMG response.
IThresh may be determined for each of the four orthogonal electrodes 1402A-1402D (
Arc Method
In one embodiment, successive directional information may take the form of an arc or wedge (or range) representing a zone that contains the nerve, according to an “arc” method described below. This successive directional information is based on stimulation current threshold “ranges,” and may be displayed (
In the bracketing process, an electrical stimulus is provided at each of the four orthogonal electrodes 1402A-1402D (
As shown in
This successive approximation information may be communicated to the surgeon in a number of easy-to-interpret fashions, including but not limited to the use of visual indicia (such as alpha-numeric characters, light-emitting elements, and/or graphics, as in
There are a number of possibilities for displaying the arc information. An arc or wedge might be displayed. Alternatively, an arrow might point to the midpoint of the arc. Another indicator might be used to illustrate the width of the arc (i.e. the uncertainty remaining in the result).
Upon completion of the bracketing process, a bisection process may determine more precisely the stimulation current thresholds. As with the bracketing process, current stimulations may be “rotated” among the stimulation electrodes so that the thresholds are refined substantially in parallel, according to the “arc” method. As with the bracketing method, the arc (wedge) 1502 containing the final direction vector may be computed and displayed (
The above-identified two-part hunting-algorithm may be further explained with reference to
The size of the brackets may then be reduced by a bisection method. A current stimulation value at the midpoint of the bracket is used, and if this results in a Vpp that is above Vthresh, then the lower half becomes the new bracket. Likewise, if the midpoint Vpp is below Vthresh, then the upper half becomes the new bracket. This bisection method is used until the bracket size has been reduced to IThresh mA. IThresh may be selected as a value falling within the bracket, but is preferably defined as the midpoint of the bracket.
The threshold-hunting algorithm of this embodiment may support three states: bracketing, bisection, and monitoring. A “stimulation current bracket” is a range of stimulation currents that bracket the stimulation current threshold IThresh. The width of a bracket is the upper boundary value minus the lower boundary value. If the stimulation current threshold IThresh of a channel exceeds the maximum stimulation current, that threshold is considered out-of-range. During the bracketing state, threshold hunting will employ the method described herein to select stimulation currents and identify stimulation current brackets for each EMG channel in range.
The initial bracketing range may be provided in any number of suitable ranges. In one embodiment, the initial bracketing range is 0.2 to 0.3 mA. If the upper stimulation current does not evoke a response, the upper end of the range should be increased. For example, the range scale factor may be 2. The stimulation current should preferably not be increased by more than 10 mA in one iteration. The stimulation current should preferably never exceed a programmed maximum stimulation current (to prevent nerve damage, injury or other undesirable effects). For each stimulation, the algorithm will examine the response of each active channel to determine whether the stimulation current falls within that bracket. Once the stimulation current threshold of each channel has been bracketed, the algorithm transitions to the bisection state.
During the bisection state (
During the monitoring state (
A method for computing the successive arc/wedge directional information from stimulation current threshold range information is described. The stimulation current threshold is presumed to be proportional to a distance to the nerve. The nerve may be modeled as a single point. Since stimulation current electrodes are in an orthogonal array, calculation of the X- and Y-dimension components of the direction vector may proceed independently. With reference to
where ie, iw, in, and is represent the stimulation current thresholds for the east, west, north, and south electrodes 802B, 802D, 802A, 802C, respectively. (The equations may be normalized to an arbitrary scale for convenience.)
As the threshold hunting method begins, the stimulation current thresholds are known only within a range of values. Therefore, the X- and Y-dimension components are known only within a range. This method provides an extension to the previous definitions, as follows:
Just as ie,min and ie,max bracket ie, x and y are bracketed by [xmin, xmax] and [ymin, ymax]. Stated another way, the point (x,y) lies within a rectangle 900 described by these boundaries, as shown in
The arc method may have several advantages. First, the arc is capable of narrowing in a relatively quick fashion as more stimulations and responses are analyzed. This method provides general directional information much faster than if the current threshold for each electrode 1402 was determined before moving on the next electrode 1402. With general directional information, it may be possible to terminate the stimulation before having the ultimate precision of the stimulation current vectors. This will result in a faster response, in many instances. The arc method may provide a real-time view of the data-analysis. This helps illustrate the value of additional stimulations to a user. This educates and empowers the user. The user can observe the progress of this method, which aids in the understanding of the time the system 20 takes to converge on the final direction vector. More frequent display updates help time “go faster” for the user. This method avoids a long pause that might seem even longer. Disclosure of the intermediate acts (narrowing arcs) in the process of finding the direction vector invites mutual trust between the user and the access system 30. An arc may provide a more intuitive visualization for neural tissue than a direction vector.
The arc method may also be useful in tracking direction as the instrument and stimulation electrodes move relative to the nerve. For example, if the uncertainty in the stimulation current threshold increases, this can be reflected in an increasing arc size.
The sequential dilation access system 34 (
In one embodiment, the surgical system 20 accomplishes this through the use of the surgical hand-piece 52, which may be electrically coupled to the K-wire 46 via a first cable connector 51a, 51b and to either the dilating cannula 48 or the working cannula 50 via a second cable connector 53a, 53b. For the K-wire 46 and working cannula 50, cables are directly connected between these accessories and the respective cable connectors 51a, 53a for establishing electrical connection to the stimulation electrode(s). In one embodiment, a pincher or clamp-type device 57 is provided to selectively establish electrical communication between the surgical hand-piece 52 and the stimulation electrode(s) on the distal end of the cannula 48. This is accomplished by providing electrical contacts on the inner surface of the opposing arms forming the clamp-type device 57, wherein the contacts are dimensioned to be engaged with electrical contacts (preferably in a male-female engagement scenario) provided on the dilating cannula 48 and working cannula 50. The surgical hand-piece 52 includes one or more buttons such that a user may selectively direct a stimulation current signal from the control unit 22 to the electrode(s) on the distal ends of the surgical access components 46-50. In an important aspect, each surgical access component 46-50 is insulated along its entire length, with the exception of the electrode(s) at their distal end. In the case of the dilating cannula 48 and working cannula 50, the electrical contacts at their proximal ends for engagement with the clamp 57 are not insulated. The EMG responses corresponding to such stimulation may be monitored and assessed in order to provide nerve proximity and/or nerve direction information to the user.
When employed in spinal procedures, for example, such EMG monitoring would preferably be accomplished by connecting the EMG harness 26 to the myotomes in the patient's legs corresponding to the exiting nerve roots associated with the particular spinal operation level (see FIGS. 11 and 20-21). In a preferred embodiment, this is accomplished via 8 pairs of EMG electrodes 27 (
In another embodiment, the K-wire 46 and dilating cannula 48 in
In the embodiment shown, the trajectory of the K-wire 46 and initial dilator 48A is such that they progress towards an intervertebral target site in a postero-lateral, trans-psoas fashion so as to avoid the bony posterior elements of the spinal column. Once the K-wire 46 is docked against the annulus of the particular intervertebral disk, cannulae of increasing diameter 48B-48D may then be guided over the previously installed cannula 48A (sequential dilation) until a desired lumen diameter is installed, as shown in
Once a nerve is detected using the K-wire 46, dilating cannula 48, or the working cannula 50, the surgeon may select the DIRECTION function to determine the angular direction to the nerve relative to a reference mark on the access components 46-50, as shown in
Where the “circles” in
Where R is the cannula radius, standardized to 1, since angles and not absolute values are measured.
After conversion from Cartesian coordinates (x,y) to polar coordinates (r,θ), then θ is the angular direction to the nerve. This angular direction may then be displayed to the user, by way of example only, as the arrow 90 shown in
After establishing an operative corridor to a surgical target site via the surgical access system 34, any number of suitable instruments and/or implants may be introduced into the surgical target site depending upon the particular type of surgery and surgical need. By way of example only, in spinal applications, any number of implants and/or instruments may be introduced through the working cannula 50, including but not limited to spinal fusion constructs (such as allograft implants, ceramic implants, cages, mesh, etc.), fixation devices (such as pedicle and/or facet screws and related tension bands or rod systems), and any number of motion-preserving devices (including but not limited to total disc replacement systems).
Segregating the Geometric and Electrical Direction Algorithm Models
There are other relationships resulting from the symmetry of the four electrodes described above:
where d0 is the distance between the nerve activation site and the midpoint between the electrodes (i.e., the origin (0, 0) or “virtual center”). These results are based purely on geometry and apply independent of an electrical model.
As described above under the “arc” method, the geometric model can be extended to define a region of uncertainty based on the uncertainty in the distance to the nerve:
In
Generalized 1-D Model
The 1-D model can be extended to two or three dimensions by the addition of electrodes.
3-D Geometric Model
Using the four co-planar electrodes (
3-D direction to the nerve is possible by comparing the distance to the nerve activation site from the k-wire electrode 2300 to that of the other electrodes.
where do (as noted above) is the distance between the nerve activation site and the midpoint between the electrodes (i.e., the origin (0, 0) or “virtual center”), and dk is the distance between the nerve activation site and the k-wire electrode 2300. 3-D direction is possible by converting from Cartesian (x, y, z) to spherical (p, θ, φ) coordinates. The arc method described above may also be extended to three dimensions. Other 3-D geometric models may be constructed. One possibility is to retain the four planar electrodes 1402A-1402D and add a fifth electrode 1404 along the side of the cannula 1400, as shown in
Another possibility is to replace the four planar electrodes 2502A-2502D with two pairs (e.g., vertices of a tetrahedron), as shown in
Electric Model
The direction algorithm described above assumes direct proportionality between distance and the stimulation current threshold, as in equation (2).
ith=Kd (6)
where ith is the threshold current, K is a proportionality constant denoting a relationship between current and distance, and d is the distance between an electrode and a nerve.
An alternative model expects the stimulation current threshold to increase with the square of distance:
ith=io+Kd2 (7)
Using the distance-squared model, the Cartesian coordinates for the nerve activation site can be derived from equations (5), (7) and the following:
where ix is the stimulation current threshold of the corresponding stimulation electrode (west, east, south or north), ik is the stimulation current threshold of the k-wire electrode 2602A (
Other sets of equations may be similarly derived for alternative electrode geometries. Note that in each case, i0 is eliminated from the calculations. This suggests that the absolute position of the nerve activation site relative to the stimulation electrodes may be calculated knowing only K. As noted above, K is a proportionality constant denoting the relationship between current and distance.
Distance or position of the neural tissue may be determined independent of nerve status or pathology (i.e., elevated i0), so long as stimulation current thresholds can be found for each electrode.
Measuring Nerve Pathology
If the distance to the nerve is known (perhaps through the methods described above), then it is possible to solve equation (8) for i0. This would permit detection of nerves with elevated stimulation thresholds, which may provide useful clinical (nerve pathology) information.
io=ith−Kd2 (10)
Removing Dependence on K
The preceding descriptions assume that the value for K is known. It is also possible to measure distance to a nerve activation site without knowing K, by performing the same measurement from two different electrode sets.
Adding the electrical model from equation (7), the dependence on K is removed. Solve equation (11) for db to get the distance in one dimension:
Finally, it is possible to solve for the value of K itself:
Although the configuration in
Electrode Redundancy
Whichever electrical model is used, the relationship expressed in equation (1) means that the current at any of the electrodes at the four compass points can be “predicted” from the current values of the other three electrodes. Using the electrical model of equation (7) yields:
Using the electrical model of equation (6) yields:
iw+ie=is+in
This provides a simple means to validate either electrical model.
Applying the tools of geometric and electrical modeling may help to create more efficient, accurate measurements of the nerve location.
While certain embodiments have been described, it will be appreciated by those skilled in the art that variations may be accomplished in view of these teachings without deviating from the spirit or scope of the present application. For example, the system 22 may be implemented using any combination of computer programming software, firmware or hardware. As a preparatory act to practicing the system 20 or constructing an apparatus according to the application, the computer programming code (whether software or firmware) according to the application will typically be stored in one or more machine readable storage mediums such as fixed (hard) drives, diskettes, optical disks, magnetic tape, semiconductor memories such as ROMs, PROMs, etc., thereby making an article of manufacture in accordance with the application. The article of manufacture containing the computer programming code may be used by either executing the code directly from the storage device, by copying the code from the storage device into another storage device such as a hard disk, RAM, etc. or by transmitting the code on a network for remote execution. As can be envisioned by one of skill in the art, many different combinations of the above may be used and accordingly the present application is not limited by the scope of the appended claims.
Claims
1. A method of finding a direction of a nerve from a surgical instrument, the method comprises:
- electrically stimulating a first stimulation electrode on a distal region of a surgical instrument configured to advance through tissue to create a distraction corridor with a first set of at least one stimulation current signal until a first initial bracket comprising a maximum stimulation current value and a minimum stimulation current value between which a first threshold stimulation current level must lie is determined;
- electrically stimulating a second stimulation electrode spaced apart from said first electrode with a second set of at least one stimulation current signal until a second initial bracket comprising a maximum stimulation current value and a minimum stimulation current value between which a second threshold stimulation current level must lie is determined;
- processing with a control unit communicatively linked to said first and second electrodes the determined first initial bracket and the determined second initial bracket, said processing including determining the first threshold stimulation current level by narrowing the first initial bracket to a first final bracket and determining the second threshold stimulation current level by narrowing the second initial bracket to a second final bracket;
- prior to completing the steps of determining the first and second threshold stimulation current levels, displaying on a display communicatively linked to said control unit, an initial indicator, based on said processing, indicating a general direction of the nerve from the surgical instrument; and
- upon completing the steps of determining the first and second threshold stimulation current levels, displaying on the display a subsequent indicator, based on said processing, indicating a more specific direction of the nerve from the surgical instrument.
2. The method of claim 1, wherein said indicator indicating the general direction of a nerve from the surgical instrument comprises displaying an arc indicating the general direction of the nerve from the surgical instrument.
3. The method of claim 2, further comprising displaying the arc indicating the general direction of the nerve from the surgical instrument and narrowing the arc as the control unit successively narrows the first and second initial brackets containing the first and second threshold stimulation current levels.
4. The method of claim 1, further comprising electrically stimulating the first and second stimulation electrodes to bisect each of the first initial bracket and the second initial bracket until the first threshold stimulation current level has been found for the first stimulation electrode and the second threshold stimulation current level has been found for the second stimulation electrode within a predetermined range of accuracy.
5. The method of claim 4, further comprising displaying the arc indicating the general direction of the nerve from the surgical instrument and narrowing the arc as the first and second initial brackets are bisected.
6. The method of claim 1, wherein at least one of the steps of determining the first initial bracket comprising a maximum stimulation current value and a minimum stimulation current value between which a first threshold stimulation current level must lie and determining the second initial bracket comprising a maximum stimulation current value and a minimum stimulation current value between which a second threshold stimulation current level must lie further comprises the step of sensing a response of the nerve depolarized by said first set of at least one stimulation signal and said second set of at least one stimulation signal.
7. The method of claim 1, further comprising the additional steps of electrically stimulating a third stimulation electrode spaced apart from said first and second electrodes with a third set of at least one of a third stimulation current signal until a third initial bracket comprising a maximum stimulation current value and a minimum stimulation current value between which a third threshold stimulation current level must lie is determined;
- electrically stimulating a fourth stimulation electrode spaced apart from said first, second, and third electrodes with a fourth set of at least one stimulation current signal until a fourth initial bracket comprising a maximum stimulation current value and a minimum stimulation current value between which a fourth threshold stimulation current level must lie is determined;
- processing with a control unit communicatively linked to said third and fourth electrodes the determined third initial bracket and the determined fourth initial bracket, said processing including determining the third threshold stimulation current level by narrowing the third initial bracket to a third final bracket and determining the fourth threshold stimulation current level by narrowing the fourth initial bracket to a fourth final bracket;
- prior to completing the steps of determining the third and fourth threshold stimulation current levels, displaying on a display communicatively linked to said control unit, an initial indicator, based on said processing, indicating a general direction of the nerve from the surgical instrument; and
- upon completing the steps of determining the third and fourth threshold stimulation current levels, displaying on the display a subsequent indicator, based on said processing, indicating a more specific direction of the nerve from the surgical instrument.
8. The method of claim 7, further comprising displaying the arc indicating the general direction of the nerve from the surgical instrument and narrowing the arc as the control unit successively narrows the first, second, third, and fourth initial brackets containing the first, second, third, and fourth threshold stimulation current levels.
9. The method of claim 7, further comprising electrically stimulating the first, second, third, and fourth stimulation electrodes to bisect each of the first initial bracket, second initial bracket, third initial bracket, and fourth initial bracket until the first threshold stimulation current level has been found for the first stimulation electrode, the second threshold stimulation current level has been found for the second stimulation electrode, the third threshold stimulation current level has been found for the third stimulation electrode, and the fourth threshold stimulation current level has been found for the fourth stimulation electrode within a predetermined range of accuracy.
10. The method of claim 9, further comprising displaying the arc indicating the general direction of the nerve from the surgical instrument and narrowing the arc as the first, second, third, and fourth initial brackets are bisected.
11. The method of claim 7, wherein the maximum stimulation current value of each of the first, second, third, and fourth initial brackets is a current intensity of a stimulation signal that first evokes a neuromuscular response of a predetermined magnitude from a muscle innervated by said nerve and the minimum stimulation current value of the first, second, third, and fourth initial brackets is a current intensity of a stimulation signal that first fails to evoke a neuromuscular response of said predetermined magnitude from said muscle.
12. The method of claim 11, wherein each of the first, second, third, and fourth initial brackets are bisected by stimulating with a current intensity at the midpoint of the bracket.
13. The method of claim 12, wherein the bisection of each bracket is repeated until the width of each bracket is reduced to a predetermined accuracy.
14. The method of claim 13, wherein the stimulation current levels for each of the first, second, third, and fourth electrodes are determined as a value within the respective first, second, third, and fourth brackets after the brackets are reduced to the predetermined accuracy.
15. The method of claim 14, further comprising the step of deriving x and y Cartesian coordinates of the general direction of the nerve with respect to said surgical instrument by using x=iw2−ie2 and y=is2−in2, where ie, iw, in, and is represent the threshold stimulation current levels for the first, second, third, and fourth electrodes.
16. The method of claim 14, further comprising the step of determining a three-dimensional vector from a reference point on the surgical instrument to a nerve.
17. The method of claim 16, further comprising the step of determining a three-dimensional vector from a reference point on the surgical instrument to a nerve by using: x = 1 4 R ( d w 2 - d e 2 ) y = 1 4 R ( d s 2 - d n 2 ) and z = 1 4 D ( d o 2 - d k 2 ).
18. The method of claim 16, further comprising the step of determining a three-dimensional vector from a reference point on the surgical instrument to a nerve by using: x = 1 4 RK ( i w - i e ) y = 1 4 RK ( i s - i n ) and z = 1 4 DK ( i c - i k ) where ix is a stimulation current threshold for a corresponding stimulation electrode (first, second, third, and fourth), ik is the stimulation current threshold of a k-wire electrode, and ic is calculated from: i c + KR 2 = 1 4 ( i w + i e + i s + i n ).
19. The method of claim 16, further comprising the step of displaying the three-dimensional vector to a user.
20. The method of claim 14, further comprising the step of processing the stimulation current thresholds by using x min = i w, min 2 - i e, m ax 2; x m ax = i w, m ax 2 - i e, min 2; y min = i s, min 2 - i n, max 2; y ma x = i s, ma x 2 - i n, min 2, where ie, iw, in, and is represent the stimulation current thresholds for the first, second, third, and fourth electrodes.
21. The method of claim 14, further comprising the step of processing the stimulation current thresholds by using x min = 1 4 R ( d w, min 2 - d e, m ax 2 ) x m ax = 1 4 R ( d w, m ax 2 - d e, m i n 2 ) y min = 1 4 R ( d s, min 2 - d n, m ax 2 ) y ma x = 1 4 R ( d s, max 2 - d n, min 2 ) where d is a distance from the first, second, third, and fourth electrodes.
22. The method of claim 1, wherein the first set of at least one stimulation signal comprises stimulation signals of sequentially doubled current intensity.
23. The method of claim 22, wherein the second set of at least one stimulation signal comprises stimulation signals of sequentially doubled current intensity.
24. The method of claim 23, wherein the maximum stimulation current value of the second initial bracket is a current intensity of a stimulation signal that first evokes a neuromuscular response of a predetermined magnitude from a muscle innervated by said nerve and the minimum stimulation current value of the second initial bracket is a current intensity of a stimulation signal that failed to evoke a neuromuscular response of said predetermined magnitude from said muscle.
25. The method of claim 22, wherein the maximum stimulation current value of the first initial bracket is a current intensity of a stimulation signal that first evokes a neuromuscular response of a predetermined magnitude from a muscle innervated by said nerve and the minimum stimulation current value of the first initial bracket is a current intensity of a stimulation signal that failed to evoke a neuromuscular response of said predetermined magnitude from said muscle.
208227 | September 1878 | Dorr |
972983 | October 1910 | Arthur |
1328624 | January 1920 | Graham |
1548184 | August 1925 | Cameron |
2704064 | March 1955 | Fizzell et al. |
2736002 | February 1956 | Oriel |
2808826 | October 1957 | Reiner et al. |
3364929 | January 1968 | Ide et al. |
3664329 | May 1972 | Naylor |
3682162 | August 1972 | Colyer |
3785368 | January 1974 | McCarthy et al. |
3830226 | August 1974 | Staub et al. |
3957036 | May 18, 1976 | Normann |
4099519 | July 11, 1978 | Warren |
4164214 | August 14, 1979 | Stark et al. |
4207897 | June 17, 1980 | Lloyd et al. |
4224949 | September 30, 1980 | Scott et al. |
4226228 | October 7, 1980 | Shin et al. |
4235242 | November 25, 1980 | Howson et al. |
4285347 | August 25, 1981 | Hess |
4291705 | September 29, 1981 | Severinghaus et al. |
4461300 | July 24, 1984 | Christensen |
4515168 | May 7, 1985 | Chester et al. |
4519403 | May 28, 1985 | Dickhudt |
4545374 | October 8, 1985 | Jacobson |
4561445 | December 31, 1985 | Berke et al. |
4562832 | January 7, 1986 | Wilder et al. |
4573448 | March 4, 1986 | Kambin |
4592369 | June 3, 1986 | Davis et al. |
4595018 | June 17, 1986 | Rantala |
4611597 | September 16, 1986 | Kraus |
4616660 | October 14, 1986 | Johns |
4633889 | January 6, 1987 | Talalla |
4658835 | April 21, 1987 | Pohndorf |
4744371 | May 17, 1988 | Harris |
4759377 | July 26, 1988 | Dykstra |
4784150 | November 15, 1988 | Voorhies et al. |
4807642 | February 28, 1989 | Brown |
4892105 | January 9, 1990 | Prass |
4913134 | April 3, 1990 | Luque |
4926865 | May 22, 1990 | Oman |
4962766 | October 16, 1990 | Herzon |
4964411 | October 23, 1990 | Johnson et al. |
5007902 | April 16, 1991 | Witt |
5058602 | October 22, 1991 | Brody |
5081990 | January 21, 1992 | Deletis |
5092344 | March 3, 1992 | Lee |
5125406 | June 30, 1992 | Goldstone et al. |
5127403 | July 7, 1992 | Brownlee |
5161533 | November 10, 1992 | Prass et al. |
5196015 | March 23, 1993 | Neubardt |
RE34390 | September 28, 1993 | Culver |
5255691 | October 26, 1993 | Otten |
5282468 | February 1, 1994 | Klepinski |
5284153 | February 8, 1994 | Raymond et al. |
5284154 | February 8, 1994 | Raymond et al. |
5299563 | April 5, 1994 | Seton |
5312417 | May 17, 1994 | Wilk |
5313956 | May 24, 1994 | Knutsson et al. |
5313962 | May 24, 1994 | Obenchain |
5327902 | July 12, 1994 | Lemmen |
5333618 | August 2, 1994 | Lekhtman et al. |
5375067 | December 20, 1994 | Berchin |
5383876 | January 24, 1995 | Nardella |
5474057 | December 12, 1995 | Makower |
5474558 | December 12, 1995 | Neubardt |
5480440 | January 2, 1996 | Kambin |
5482038 | January 9, 1996 | Ruff |
5484437 | January 16, 1996 | Michelson |
5509893 | April 23, 1996 | Pracas |
5540235 | July 30, 1996 | Wilson |
5549656 | August 27, 1996 | Reiss |
5560372 | October 1, 1996 | Cory |
5566678 | October 22, 1996 | Cadwell |
5569248 | October 29, 1996 | Matthews |
5571149 | November 5, 1996 | Liss et al. |
5579781 | December 3, 1996 | Cooke |
5593429 | January 14, 1997 | Ruff |
5599279 | February 4, 1997 | Slotman et al. |
5601608 | February 11, 1997 | Mouchawar |
5630813 | May 20, 1997 | Kieturakis |
5667508 | September 16, 1997 | Errico et al. |
5671752 | September 30, 1997 | Sinderby et al. |
5681265 | October 28, 1997 | Maeda et al. |
5707359 | January 13, 1998 | Bufalini |
5711307 | January 27, 1998 | Smits |
5728046 | March 17, 1998 | Mayer et al. |
5741253 | April 21, 1998 | Michelson |
5759159 | June 2, 1998 | Masreliez |
5772661 | June 30, 1998 | Michelson |
5775331 | July 7, 1998 | Raymond et al. |
5776144 | July 7, 1998 | Leysieffer et al. |
5779642 | July 14, 1998 | Nightengale |
5785658 | July 28, 1998 | Benaron |
5797854 | August 25, 1998 | Hedgecock |
5806522 | September 15, 1998 | Katims |
5814073 | September 29, 1998 | Bonutti |
5830151 | November 3, 1998 | Hadzic et al. |
5851191 | December 22, 1998 | Gozani |
5853373 | December 29, 1998 | Griffith et al. |
5860973 | January 19, 1999 | Michelson |
5862314 | January 19, 1999 | Jeddeloh |
5872314 | February 16, 1999 | Clinton |
5885210 | March 23, 1999 | Cox |
5885219 | March 23, 1999 | Nightengale |
5888196 | March 30, 1999 | Bonutti |
5902231 | May 11, 1999 | Foley et al. |
5928139 | July 27, 1999 | Koros et al. |
5928158 | July 27, 1999 | Aristides |
5935131 | August 10, 1999 | Bonutti |
5938688 | August 17, 1999 | Schiff |
5947964 | September 7, 1999 | Eggers et al. |
5976094 | November 2, 1999 | Gozani et al. |
6004262 | December 21, 1999 | Putz et al. |
6011985 | January 4, 2000 | Athan et al. |
6024696 | February 15, 2000 | Hoftman et al. |
6027456 | February 22, 2000 | Feler et al. |
6038469 | March 14, 2000 | Karlsson et al. |
6038477 | March 14, 2000 | Kayyali |
6050992 | April 18, 2000 | Nichols |
6074343 | June 13, 2000 | Nathanson et al. |
6104957 | August 15, 2000 | Alo et al. |
6104960 | August 15, 2000 | Duysens et al. |
6119068 | September 12, 2000 | Kannonji |
6120503 | September 19, 2000 | Michelson |
6126660 | October 3, 2000 | Dietz |
6128576 | October 3, 2000 | Nishimoto |
6132386 | October 17, 2000 | Gozani et al. |
6132387 | October 17, 2000 | Gozani et al. |
6135965 | October 24, 2000 | Tumer et al. |
6138681 | October 31, 2000 | Chen et al. |
6139493 | October 31, 2000 | Koros et al. |
6139545 | October 31, 2000 | Utley |
6146335 | November 14, 2000 | Gozani |
6161047 | December 12, 2000 | King et al. |
6181961 | January 30, 2001 | Prass |
6196969 | March 6, 2001 | Bester et al. |
6206826 | March 27, 2001 | Mathews et al. |
6224549 | May 1, 2001 | Drongelen |
6259945 | July 10, 2001 | Epstein et al. |
6264651 | July 24, 2001 | Underwood et al. |
6266558 | July 24, 2001 | Gozani et al. |
6273905 | August 14, 2001 | Streeter |
6292701 | September 18, 2001 | Prass et al. |
6306100 | October 23, 2001 | Prass |
6312392 | November 6, 2001 | Herzon |
6325764 | December 4, 2001 | Griffith et al. |
6334068 | December 25, 2001 | Hacker |
6348058 | February 19, 2002 | Melkent et al. |
6360750 | March 26, 2002 | Gerber et al. |
6393325 | May 21, 2002 | Mann et al. |
6425859 | July 30, 2002 | Foley et al. |
6425901 | July 30, 2002 | Zhu et al. |
6450952 | September 17, 2002 | Rioux et al. |
6451015 | September 17, 2002 | Rittman, III et al. |
6466817 | October 15, 2002 | Kaula et al. |
6500128 | December 31, 2002 | Marino |
6507755 | January 14, 2003 | Marino et al. |
6535759 | March 18, 2003 | Epstein et al. |
6564078 | May 13, 2003 | Marino et al. |
6579244 | June 17, 2003 | Goodwin |
6582441 | June 24, 2003 | He et al. |
6585638 | July 1, 2003 | Yamamoto |
6618626 | September 9, 2003 | West, Jr. et al. |
6620157 | September 16, 2003 | Dabney et al. |
6719692 | April 13, 2004 | Kleffner et al. |
6760616 | July 6, 2004 | Hoey et al. |
6770074 | August 3, 2004 | Michelson |
6796985 | September 28, 2004 | Bolger et al. |
6810281 | October 26, 2004 | Brock et al. |
6819956 | November 16, 2004 | DiLorenzo |
6847849 | January 25, 2005 | Mamo et al. |
6849047 | February 1, 2005 | Goodwin |
6855105 | February 15, 2005 | Jackson, III et al. |
6902569 | June 7, 2005 | Parmer et al. |
6926728 | August 9, 2005 | Zucherman et al. |
6929606 | August 16, 2005 | Ritland |
6945933 | September 20, 2005 | Branch et al. |
6951538 | October 4, 2005 | Ritland |
7047082 | May 16, 2006 | Schrom |
7050848 | May 23, 2006 | Hoey et al. |
7079883 | July 18, 2006 | Marino et al. |
7089059 | August 8, 2006 | Pless |
7177677 | February 13, 2007 | Kaula et al. |
7207949 | April 24, 2007 | Miles et al. |
7258688 | August 21, 2007 | Shah et al. |
7294127 | November 13, 2007 | Leung et al. |
7310546 | December 18, 2007 | Prass |
7473222 | January 6, 2009 | Dewey et al. |
7481766 | January 27, 2009 | Lee et al. |
7522953 | April 21, 2009 | Kaula et al. |
7582058 | September 1, 2009 | Miles et al. |
7643884 | January 5, 2010 | Pond et al. |
7657308 | February 2, 2010 | Miles et al. |
7664544 | February 16, 2010 | Miles et al. |
7691057 | April 6, 2010 | Miles et al. |
20010039949 | November 15, 2001 | Loubser |
20010056280 | December 27, 2001 | Underwood et al. |
20020007129 | January 17, 2002 | Marino |
20020010392 | January 24, 2002 | Desai |
20020072686 | June 13, 2002 | Hoey et al. |
20020123780 | September 5, 2002 | Grill et al. |
20020161415 | October 31, 2002 | Cohen et al. |
20020193843 | December 19, 2002 | Hill et al. |
20030032966 | February 13, 2003 | Foley et al. |
20030078618 | April 24, 2003 | Fey et al. |
20030105503 | June 5, 2003 | Marino |
20040199084 | October 7, 2004 | Kelleher et al. |
20040225228 | November 11, 2004 | Ferree |
20050004593 | January 6, 2005 | Simonson |
20050004623 | January 6, 2005 | Miles et al. |
20050033380 | February 10, 2005 | Tanner et al. |
20050075578 | April 7, 2005 | Gharib et al. |
20050080320 | April 14, 2005 | Lee et al. |
20050080418 | April 14, 2005 | Simonson et al. |
20050119660 | June 2, 2005 | Burlion |
20050149035 | July 7, 2005 | Pimenta et al. |
20050182454 | August 18, 2005 | Gharib et al. |
20050256582 | November 17, 2005 | Ferree |
20060025703 | February 2, 2006 | Miles et al. |
20060052828 | March 9, 2006 | Kim et al. |
20060069315 | March 30, 2006 | Miles et al. |
20060224078 | October 5, 2006 | Hoey et al. |
20070016097 | January 18, 2007 | Farquhar et al. |
20070198062 | August 23, 2007 | Miles et al. |
20070293782 | December 20, 2007 | Marino |
20080015612 | January 17, 2008 | Urmey |
20080039914 | February 14, 2008 | Cory et al. |
20080058606 | March 6, 2008 | Miles et al. |
20080064976 | March 13, 2008 | Kelleher et al. |
20080064977 | March 13, 2008 | Kelleher et al. |
20080065178 | March 13, 2008 | Kelleher et al. |
20080071191 | March 20, 2008 | Kelleher et al. |
20090192403 | July 30, 2009 | Gharib et al. |
20090204016 | August 13, 2009 | Gharib et al. |
20090204176 | August 13, 2009 | Miles et al. |
20090209879 | August 20, 2009 | Kaula et al. |
299 08 259 | July 1999 | DE |
0 759 307 | February 1997 | EP |
0 972 538 | January 2000 | EP |
2 795 624 | January 2001 | FR |
2 796 846 | February 2001 | FR |
2001-299718 | October 2001 | JP |
00/38574 | July 2000 | WO |
WO-0038574 | July 2000 | WO |
00/66217 | November 2000 | WO |
00/67645 | November 2000 | WO |
WO-0066217 | November 2000 | WO |
01/03604 | January 2001 | WO |
01/37728 | May 2001 | WO |
03/005887 | January 2003 | WO |
WO 03005887 | January 2003 | WO |
WO-03026482 | April 2003 | WO |
03/037170 | May 2003 | WO |
WO 03037170 | May 2003 | WO |
WO-03037170 | May 2003 | WO |
2004/012809 | February 2004 | WO |
2005/013805 | February 2005 | WO |
WO-2005013805 | February 2005 | WO |
2006/084193 | August 2006 | WO |
- Calancie, Blair et al. “Stimulus-evoked EMG Monitoring During Transpedicular Lumbrosacral Spine Instrumentation: Initial Clinical Results”. 1994. Spine. vol. 19, No. 24, pp. 2780-2786.
- “Brackmann II EMG System”, Medical Electronics, (1999),4 pages.
- “Electromyography System”, International Search Report, International Application No. PCT/US00/32329,(Apr. 27, 2001),9 pages.
- “Nerve Proximity and Status Detection System and Method”, International Search Report, International Application No. PCT/US01/18606,(Oct. 18, 2001),6 pages.
- “Neurovision SE Nerve Locator/Monitor”, RLN Systems, Inc. Operators Manual, (1999),22 pages.
- “Relative Nerve Movement and Status Detection System and Method”, International Search Report, International Application No. PCT/US01/18579,(Jan. 15, 2002),6 pages.
- “System and Method for Determination Nerve Proximity, Direction, and Pathology During Surgery”, International Search Report, International Application No. PCT/US02/22247,(Mar. 27, 2003),4 pages.
- “System and Methods for Determining Nerve Direction to a Surgical Instrument”, International Search Report, International Application No. PCT/US03/02056,(Aug. 12, 2003),5 pages.
- “Systems and Methods for Performing Percutaneous Pedicle Integrity Assessments”, International Search Report, International Application No. PCT/US02/35047,(Aug. 11, 2003),5 pages.
- “Systems and Methods for Performing Surgery Procedures and Assessments”, International Search Report, International Application No. PCT/US02/30617,(Jun. 5, 2003),4 pages.
- “The Brackmann II EMG Monitoring System”, Medical Electronics Co. Operator's Manual Version 1.1, (1995),50 pages.
- “The Nicolet Viking IV”, Nicolet Biomedical Products, (1999),6 pages.
- Anderson, D. G., et al., “Pedicle screws with high electrical resistance: a potential source of error with stimulus-evoked EMG”, Spine. 27(14):, Department of Orthopaedic of Virginia,(Jul. 15, 2002),1577-1581.
- Bose, Bikash , et al., “Neurophysiologic Monitoring of Spinal Nerve Root Function During Instrumented Posterior Lumbar Spine Surgery”, Spine, 27(13), (2002),1444-1450.
- Calancie, Blair , et al., “Stimulus-Evoked EMG Monitoring During Transpedicular Lumbosacral Spine Instrumentation”, Spine, 19(24), (1994),2780-2786.
- Clements, David , et al., “Evoked and Spontaneous Electromyography to Evaluate Lumbosacral Pedicle Screw Placement”, Spine, 21(5), (1996),600-604.
- Danesh-Clough, T. , et al., “The use of evoked EMG in detecting misplaced thoracolumbar pedicle screws”, Spine. 26(12), Orthopaedic Department, Dunedin Hospital,(Jun. 15, 2001),1313-1316.
- Darden, B. V., et al., “A comparison of impedance and electromyogram measurements in detecting the presence of pedicle wall breakthrough”, Spine. 23(2), Charlotte Spine Center, North Carolina,(Jan. 15, 1998),256-262.
- Ebraheim, N. A., “Anatomic relations between the lumbar pedicle and the adjacent neural structures”, Spine. 22(20), Department of Orthopaedic Surgery, Medical College of Ohio,(Oct. 15, 1997),2338-2341.
- Ford, Douglas , et al., “Electrical Characteristics of Peripheral Nerve Stimulators Implications for Nerve Localization”, Regional Anesthesia, 9, (1984),73-77.
- Glassman, Steven , et al., “A Prospective Analysis of Intraoperative Electromyographic Monitoring of Pedicle Screw Placement With Computed Tomographic Scan Confirmation”, Spine , 20(12), (1995),1375-1379.
- Greenblatt, Gordon , et al., “Needle Nerve Stimulator-Locator: Nerve Blocks with a New Instrument for Locating Nerves”, Anesthesia & Analgesia, 41(5), (1962),599-602.
- Haig, “Point of view”, Spine 27 (24), 2819.
- Haig, A. J., et al., “The relation among spinal geometry on MRI, paraspinal electromyographic abnormalities, and age in persons referred for electrodiagnostic testing of low back symptoms”, Spine. 27(17), Department of Physical Medicine and Rehabilitation, University of Michigan,(Sep. 1, 2002),1918-1925.
- Holland, N. R., et al., “Higher electrical stimulus intensities are required to activate chronically compressed nerve roots. Implications for intraoperative electromyographic pedicle screw testing”, Spine. 23(2), Department of Neurology, John Hopkins University School of Medicine,(Jan. 15, 1998),224-227.
- Holland, Neil , “Intraoperative Electromyography During Thoracolumbar Spinal Surgery”, Spine, 23(17), (1998),1915-1922.
- Lenke, Lawrence , et al., “Triggered Electromyographic Threshold for Accuracy of Pedicle Screw Placement”, Spine, 20 (14), (1995),1585-1591.
- Maguire, J. , et al., “Evaluation of Intrapedicular Screw Position Using Intraoperative Evoked Electromyography”, Spine, 20(9), (1995),1068-1074.
- Martin, David , et al., “Initiation of Erection and Semen Release by Rectal Probe Electrostimulation (RPE)”, The Williams & Wilkins Co., (1983),637-642.
- Minahan, R. E., et al., “The effect of neuromuscular blockade on pedicle screw stimulation thresholds”, Spine. 25(19), Department of Neurology, Johns Hopkins University, School of Medicine,(Oct. 1, 2000),2526-2530.
- Pither, Charles , et al., ““The Use of Peripheral Nerve Stimulators for Regional Anesthesia: Review of Experimental Characteristics, Technique, and Clinical Applications””, Regional Anesthesia, (1985),10:47-53.
- Raj, P. , et al., “Infraclavicular Brachial Plexus Block—A New Approach”, Anesthesia and Analgesia, (52)6, (1973),897-904.
- Raj, P. , et al., “The Use of Peripheral Nerve Stimulators for Regional Anesthesia”, Clinical Issues in Regional Anesthesia, 1 (4), (1985),1-6.
- Raj, P. , et al., “Use of the nerve Stimulator of Peripheral Blocks”, Regional Anesthesia, (Apr.-Jun. 1980),14-21.
- Raymond, Stephen , et al., “The Nerve Seeker: A System for Automated Nerve Localization”, Regional Anesthesia, 17(3), (1992),151-162.
- Shafik, Ahmed , “Cavernous Nerve Simulation through an Extrapelvic Subpubic Approach: Role in Pencil Erection”, Eur. Urol, 26, (1994),98-102.
- Toleikis, J. , et al., “The Usefulness of Electrical Stimulation for Assessing Pedicle Screw Replacements”, Journal of Spinal Disorder, 13(4), (2000),283-289.
- “Electromyography System,” International Search report from International Application No. PCT/US00/32329, Apr. 27, 2001, 9 pages.
- “Nerve Proximity and Status Detection System and Method,” International Search Report from International Application No. PCT/US01/18606, Oct. 18, 2001, 6 pages.
- “Relative Nerve Movement and Status Detection System and Method,” International Search Report from International Application No. PCT/US01/18579, Jan. 15, 2002, 6 pages.
- “System and Method for Determining Nerve Proximity Direction and Pathology During Surgery,” International Search Report from International Application No. PCT/US02/22247, Mar. 27, 2003, 4 pages.
- “System and Methods for Determining Nerve Direction to a Surgical Instrument,” International Search Report from International Application No. PCT/US03/02056, Aug. 12, 2003, 5 pages.
- “Systems and Methods for Performing Percutaneous Pedicle Integrity Assessments,” International Search Report from International Application No. PCT/US02/35047, Aug. 11, 2003, 5 pages.
- “Systems and Methods for Performing Surgery Procedures and Assessments,” International Search Report from International Application No. PCT/US02/30617, Jun. 5, 2003, 4 pages.
- “Systems and Methods for Performing Neurophysiologic Assessments During Spine Surgery,” International Search Report from International Application No. PCT/US06/03966, Oct. 23, 2006, 5 pages.
- “Multi-Channel Stimulation Threshold Detection Algorithm for Use in Neurophysiology Monitoring,” International Search Report from International Application No. PCT/US06/37013, Mar. 19, 2007, 10 pages.
- Lenke et al., “Triggered Electromyographic Threshold for Accuracy of Pedicle Screw Placement,” Spine, 1995, 20(4): 1585-1591.
- “Brackmann II EMG System,” Medical Electronics, 1999, 4 pages.
- “Neurovision SE Nerve Locator/Monitor,” RLN Systems Inc. Operator's Manual, 1999, 22 pages.
- “The Brackmann II EMG Monitoring System,” Medical Electronics Co. Operator's Manual Version 1.1, 1995, 50 pages.
- “The Nicolet Viking IV,” Nicolet Biomedical Products, 1999, 6 pages.
- Anderson et al., “Pedicle screws with high electrical resistance: a potential source of error with stimulus-evoked EMG,” Spine, 2002, 27(14): 1577-1581.
- Bose et al., “Neurophysiologic Monitoring of Spinal Nerve Root Function During Instrumented Posterior Lumber Spine Surgery,” Spine, 2002, 27(13):1444-1450.
- Calancie et al., “Stimulus-Evoked EMG Monitoring During Transpedicular Lumbosacral Spine Instrumentation,” Spine, 1994, 19(24): 2780-2786.
- Clements et al., “Evoked and Spontaneous Electromyography to Evaluate Lumbosacral Pedicle Screw Placement,” Spine, 1996, 21(5): 600-604.
- Danesh-Clough et al., “The Use of Evoked EMG in Detecting Misplaced Thoracolumbar Pedicle Screws,” Spine, 2001, 26(12): 1313-1316.
- Darden et al., “A Comparison of Impedance and Electromyogram Measurements in Detecting the Presence of Pedicle Wall Breakthrough,” Spine, 1998, 23(2): 256-262.
- Ebraheim et al., “Anatomic Relations Between the Lumbar Pedicle and the Adjacent Neural Structures,” Spine, 1997, 22(20): 2338-2341.
- Ford et al. “Electrical Characteristics of Peripheral Nerve Stimulators Implications for Nerve Localization,” Regional Anesthesia, 1984, 9: 73-77.
- Glassman et al., “A Prospective Analysis of Intraoperative Electromyographic Monitoring of Pedicle Screw Placement With Computed Tomographic Scan Confirmation,” Spine, 1995, 20(12): 1375-1379.
- Greenblatt et al., “Needle Nerve Stimulator-Locator: Nerve Blocks with a New Instrument for Locating Nerves,” Anesthesia and Analgesia, 1962, 41(5): 599-602.
- Haig, “Point of view,” Spine, 2002, 27(24): 2819.
- Haig et al., “The Relation Among Spinal Geometry on MRI, Paraspinal Electromyographic Abnormalities, and Age in Persons Referred for Electrodiagnostic Testing of Low Back Symptoms,” Spine, 2002, 27(17): 1918-1925.
- Holland et al., “Higher Electrical Stimulus Intensities are Required to Activate Chronically Compressed Nerve Roots: Implications for Intraoperative Electromyographic Pedicle Screw Testing,” Spine, 1998, 23(2): 224-227.
- Holland, “Intraoperative Electromyography During Thoracolumbar Spinal Surgery,” Spine, 1998, 23(17): 1915-1922.
- Journee et al., “System for Intra-Operative Monitoring of the Cortical Integrity of the Pedicle During Pedicle Screw Placement in Low-Back Surgery: Design and Clinical Results,” Sensory and Neuromuscular Diagnostic Instrumentation and Data Analysis I, 18th Annual International Conference on Engineering in Medicine and Biology Society, Amsterdam, 1996, pp. 144-145.
- Maguire et al., “Evaluation of Intrapedicular Screw Position Using Intraoperative Evoked Electromyography,” Spine, 1995, 20(9): 1068-1074.
- Martin et al. “Initiation of Erection and Semen Release by Rectal Probe Electrostimulation (RPE),” The Journal of Urology, 1983, 129: 637-642.
- Minahan et al., “The Effect of Neuromuscular Blockade on Pedicle Screw Stimulation Thresholds,” Spine, 2000, 25(19): 2526-2530.
- Pither et al., “The Use of Peripheral Nerve Stimulators for Regional Anesthesia: Review of Experimental Characteristics Technique and Clinical Applications,” Regional Anesthesia, 1985, 10:49-58.
- Raj et al., “Infraclavicular Brachial Plexus Block—A New Approach,” Anesthesia and Analgesia, 1973, (52)6: 897-904.
- Raj et al., “The Use of Peripheral Nerve Stimulators for Regional Anesthesia,” Clinical Issues in Regional Anesthesia, 1985, 1(4):1-6.
- Raj et al., “Use of the Nerve Stimulator for Peripheral Blocks,” Regional Anesthesia, 1980, pp. 14-21.
- Raymond et al., “The Nerve Seeker: A System for Automated Nerve Localization,” Regional Anesthesia, 1992, 17(3): 151-162.
- Shafik, “Cavernous Nerve Simulation through an Extrapelvic Subpubic Approach: Role in Penile Erection,” Eur. Urol, 1994, 26: 98-102.
- Toleikis et al., “The Usefulness of Electrical Stimulation for Assessing Pedicle Screw Replacements,” Journal of Spinal Disorder, 2000, 13(4): 283-289.
- Moed et al., “Insertion of an iliosacral implant in an animal model,” Journal of Bone and Joint Surgery, 1999, 81A(11): 1529-1537.
- “NIM-Response, so advanced . . . yet so simple,” XoMed, Inc., 1999, 12 pages.
- Moed et al., “Intraoperative monitoring with stimulus-evoked electromyography during placement of iliosacral screws,” The Journal of Bone and Joint Surgery, 1998, 81A(4): 10 pages.
- “New data analyzer combines the functions of six instruments in one unit,” News Release, Nov. 11, 1987, 3 pages.
- “NuVasive's spine surgery system cleared in the US,” Pharm & Medical Industry Week, Dec. 10, 2001, 1 page.
- “Risk Capital Funds,” Innovation, Mar. 6, 1990, 172: 3 pages.
Type: Grant
Filed: Jul 15, 2005
Date of Patent: Apr 3, 2012
Patent Publication Number: 20070016097
Assignee: NuVasive, Inc. (San Diego, CA)
Inventors: Allen Farquhar (Portland, OR), James Gharib (San Diego, CA), Norbert Kaula (Arvada, CO), Jeffrey Blewett (San Diego, CA), Goretti Medeiros, legal representative (Plantsville, CT)
Primary Examiner: Max Hindenburg
Assistant Examiner: John Pani
Attorney: Jonathan Spangler
Application Number: 11/182,545
International Classification: A61B 5/05 (20060101); A61B 5/04 (20060101); A61B 18/04 (20060101);